Changes in Balance of Accumulated Other Comprehensive Loss, Net of Income Taxes (Detail) - USD ($) $ in Millions |
12 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|||||||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | |||||||||||
| Beginning Balance | $ 3,097 | $ 3,400 | $ 4,918 | ||||||||
| Other comprehensive loss before reclassifications | (1,232) | (424) | (2,973) | ||||||||
| Amounts reclassified from AOCL | |||||||||||
| Recognition of net actuarial losses | 938 | 1,109 | 806 | ||||||||
| Amortization of net prior service credits | (239) | (259) | (100) | ||||||||
| Recognition of net prior service credits from divestiture of IS&GS segment | [1] | (134) | |||||||||
| Other | 9 | [1] | (2) | ||||||||
| Total reclassified from AOCL | 574 | 850 | 704 | ||||||||
| Other comprehensive (loss) income, net of tax | (658) | 426 | (2,269) | ||||||||
| Ending Balance | 1,606 | 3,097 | 3,400 | ||||||||
| Postretirement Benefit Plan Adjustments | |||||||||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | |||||||||||
| Beginning Balance | (11,314) | (11,813) | [2] | (9,649) | [2] | ||||||
| Other comprehensive loss before reclassifications | (1,232) | (351) | (2,870) | ||||||||
| Amounts reclassified from AOCL | |||||||||||
| Recognition of net actuarial losses | 938 | 1,109 | 806 | ||||||||
| Amortization of net prior service credits | (239) | (259) | (100) | ||||||||
| Recognition of net prior service credits from divestiture of IS&GS segment | [1] | (134) | |||||||||
| Total reclassified from AOCL | 565 | 850 | 706 | ||||||||
| Other comprehensive (loss) income, net of tax | (667) | 499 | (2,164) | ||||||||
| Ending Balance | (11,981) | [2] | (11,314) | (11,813) | [2] | ||||||
| Other, net | |||||||||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | |||||||||||
| Beginning Balance | (130) | (57) | [2] | 48 | [2] | ||||||
| Other comprehensive loss before reclassifications | (73) | (103) | |||||||||
| Amounts reclassified from AOCL | |||||||||||
| Other | 9 | [1] | (2) | ||||||||
| Total reclassified from AOCL | 9 | (2) | |||||||||
| Other comprehensive (loss) income, net of tax | 9 | (73) | (105) | ||||||||
| Ending Balance | (121) | [2] | (130) | (57) | [2] | ||||||
| AOCI Attributable to Parent | |||||||||||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | |||||||||||
| Beginning Balance | (11,444) | (11,870) | [2] | (9,601) | [2] | ||||||
| Amounts reclassified from AOCL | |||||||||||
| Other comprehensive (loss) income, net of tax | (658) | 426 | (2,269) | ||||||||
| Ending Balance | $ (12,102) | [2] | $ (11,444) | $ (11,870) | [2] | ||||||
| |||||||||||